For all intents and purposes, both these are superb lenses and there is very little difference in their practical resolution.

At 24 mm the 24-105 mm lens is definitely better at the edges at f4 and f5.6. This finding is slightly surprising to me as f4 is the maximum aperture for the 24-105 mm lens, whereas the 24-70 mm is stopped down by one stop. By f8 the lenses are hard to tell apart. They are equally good at the centre.

At 35 mm the lenses are practically identical and Iíd only give a very slight edge to the new lens, and only at f4. The difference is more one of contrast than resolution, to my eyes. The 24 -70 mm seems to have just a teeny bit of flare around small details.

At 50 mm the same applies; a tad better contrast from the new lens but otherwise itís hard to discern any difference.

At 70 mm I canít tell any difference between the two lenses.In addition to eye-balling the screen with the pictures at 100%, I made a couple of 16 by 20 inch prints at the highest resolution my Epson 4000 can muster. I cannot see any difference in the results. From the point of view of a practical, working photographer, as opposed to an optical physicist working on a sophisticated bench, these lenses are essentially identical in their resolution.

If there has to be a winner here, itís the 24-105 mm lens on account of higher contrast. The baffle mentioned above appears quite effective. I also feel that f4 is a very practical aperture for this lens, even though itís then wide open.

^^ I'm going for 24-105 as a hobbyist. Bring it anywhere lens. But I'm for 24-70 if and only if portrait photography is my profession. And yes, it's darn heavy.

24-70 is not exactly a portrait lens, it's more of a "wedding" lens. you'll be wanting a longer lens for portraits, otherwise you'll be often at the long end of the lens. 24-105 would be better for that; easier to hide distracting backgrounds and less funky distortions that you get from a wider lens. in a studio where you can control everything, primes still rock.

kaya nga in the end, the choice is really in the shooting style. In my case, lowering the shutter speed is a big no-no. Increasing ISO in a situation where an F/2.8 and ISO 1600 is needed as a minimum wlll also be a problem

kaya nga in the end, the choice is really in the shooting style. In my case, lowering the shutter speed is a big no-no. Increasing ISO in a situation where an F/2.8 and ISO 1600 is needed as a minimum wlll also be a problem

True. That's why I got the 17-55, doesn't have the red ring but sure gives me the IQ I love!